To get the plane prices, we calculated the distance between each country's capital city airport and the second-largest city with an airport. Then we calculated the average costs of flights using Skyscanner and calculated the cost per 100km based on the distance between airports.

To get prices for buses and trains, we found a bus and train route to a town or city that was 100km away from the capital city. Then using the most popular travel website, we calculated the price of a ticket by taking an average from the highest and lowest fares. We then worked out how much it would cost to travel 100km.